/Engine/Source/Runtime/Projects/Public/Interfaces/IProjectManager.h
UseIsCurrentProjectDirty()to tell whether the project was actually modified.
False on failure to update the current project descriptor.
bool SetPluginEnabled ( const [FString](API\Runtime\Core\Containers\FString) & PluginName, bool bEnabled, [FText](API\Runtime\Core\Internationalization\FText) & OutFailReason )